A healthy living blog from Marshfield Clinic Health System

What your nails reveal about your health

Woman rubbing her hands - What your nails say about your health

Brittle nails can be attributed to aging, poor moisturization or malnutrition.

Dr. Erik Stratman, a Marshfield Clinic dermatologist, discusses five things your nails may say about your health and when to see a specialist.

Yellow nails

Nail polish residue

Yellowish-orange or -brown nail discoloration commonly is caused by nail polish residue.

“Some patients present to our office concerned nail discoloration means something terrible when, in fact, it’s staining left behind from polish,” Stratman said.


More than half of patients over 60 years old experience at least one infected toenail because of fungus. This can cause irregular yellowing of the nails, particularly at the nail ends. In most cases this isn’t concerning. However, risk for other infections increase in patients with uncontrolled diabetes or leg cellulitis.

Nails can infect the skin of the feet, such as with Athlete’s feet. Little cracks in the skin of the feet from this fungus infection can allow bad bacteria to infect the legs or lead to sores that heal poorly in diabetic skin.

Yellow nail syndrome

Probably the most rare cause of discoloration. Patients with yellow nail syndrome develop thickened, curved nails that stop growing.

This can signify lung and respiratory problems and is often associated with swelling of arms and legs from accumulating fluid.

Dry, cracked or brittle nails


Dry, cracked and brittle nails are common for older people.

Poor moisturization

Just like our skin can become dry in winter or from using harsh soaps, nails can become dry and cracked from poor moisturization.

“Applying a daily white petrolatum jelly coating to the nails after soaking in water for 15-20 minutes can help reverse dry, cracked or brittle nails,” Stratman said.


Brittle nails also can be caused by poor nutrition.

“If your nails are brittle or peel, make sure your diet is healthy,” he said. “Taking a daily multivitamin including B vitamins may help.”

Use this handy tip sheet for a balanced diet with healthy portions.

Nails with white spotsWhat your nails say about your health - chart

Active life? No problem.

White spots are common on nails, especially in patients active with their hands.

Often, white spots on nails come from trauma by minor nicks and bangs not traumatic enough to cause bluish-purple bruising.

Solid white? See the doc.

If nails are solid white where half the nail is discolored horizontally, see your dermatologist or primary care doctor.

Nails with pitting

Signs of skin or hair diseases

The birthplace of the nail underneath the cuticle region is called the matrix.

When certain areas of the matrix are inflamed, pitting can occur as the nail grows.

“It can look like someone took a hammer and nail and made a little tap with it in several places on the nail,” Stratman said.

Pitting most commonly occurs with a skin disease called psoriasis, but can occur in a variety of diseases including eczema and alopecia areata.

Nails with vertical or horizontal ridges

Vertical ridges, aging

These are common with aging and typically do not typically signify health concern.

If cosmetically bothersome, buffing ridges with emery boards or nail care devices can help.

Horizontal ridges: Thumb or index fingers

When horizontal ridges occur only on the thumbs and index fingers in a series of hatch marks along the central nail, it is often due to picking, known as habit-tic nail deformity. Unconscious picking is the most common reason for horizontal ridges. 

Horizontal ridges: All nails

When horizontal ridges are present on all nails, this may represent Beau’s lines.

Beau’s lines usually are caused by physical stress, such as serious illness or chemotherapy. Sometimes severe psychological stressors cause Beau’s lines, too.

When the body is under significant physical or mental stress, it shuts down all nonessential energy expenditures in the body. The first things halted during stress are hair and nail growth.

“These deep horizontal ridges are most commonly seen in patients undergoing cycles of chemotherapy,” Stratman said. “Crash diets also can cause such lines.”

When the stress is over, the body allows nails to grow normally again, but not until there has been a horizontal indentation line of growth arrest. Usually lines are seen a month or two after resolution of the stressor, as the new nail grows.

When to see a provider

Vertical pigmented streak

The most serious nail concern is a vertical pigmented streak on a single nail.

Sometimes this occurs just from having darker skin tones, but other times atypical moles or deadly skin cancers, melanomas, arise under the nail in the matrix. This can result in a vertical pigmented streak.

Getting skin cancer where ‘the sun don’t shine’

Anyone with a vertical pigmented streak should see a provider skilled in looking at nail disease, Stratman said. Sometimes a biopsy is necessary to determine the nature of the pigmented streak.

Talk to your doctor

It is okay to seek professional advice on any nail concern. Seeing a dermatologist, podiatrist, hand specialist or other professionals skilled in management of nail disease is a good first step to getting correct information.

Find a Marshfield Clinic doctor.

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